The Electric Dog of Hammond and Miessner Explained – Everything You Need To Know

The Electric Dog demonstration

The Electric Dog of Hammond and Miessner Explained – Everything You Need To Know

Electric Dog of Hammond and Miessner History 

Seleno, the Electric Dog, was invented in 1912 and was considered the ancestor of almost all self-directing robots. It was designed by John Hays Hammond Jr. (1888 – 1965) and Benjamin Franklin Miessner (1890 – 1976). Both were young Americans who were experts in radio-controlled devices. They worked in what was known as “radiodynamics” or what is also called the wireless control of mobile torpedoes. This specific area of development is also called self-acting automata.

The pair worked together, pooling their talents and expertise to make the Electric Dog a success. Hammond started the project and brought together the needed funding. Miessner refined the design and ultimately built the device. It’s important to note that the Electric Dog itself was not a patented invention, but the technology that was used to help develop it was.

Quick Facts

John Hays Hammond Jr. and Benjamin Franklin Miessner
Original Use
To show how light can change electrical properties of selenium
The Electric Dog demonstration


Electric Dog

Two years after inventing the Electric Dog, Miessner presented the device to the Purdue Engineering Review under the official title, “electric dog.” The invention became known thereafter as the Electric Dog. Miessner explained how the dog behaved in Radiodynamics: The Wireless Control of Torpedoes and Other Mechanisms [Miessner, 1916].

The Electric Dog was built to provide a mobile mechanism that would respond to light signals using selenium cells. It was likely called a “dog” because it was able to obey the instructor’s commands. This was certainly a strange looking dog, with three legs and it didn’t bark! It was, however, an interesting invention that got people’s attention. The Electric Dog was a fun way to help people learn about science and what was ultimately related to the future of robotic inventions.

Electric Dog of Hammond and Miessner: How It Worked

To understand how the Electric Dog worked, it’s important to understand what selenium is and how it works. Selenium is one of the elements on the periodic table. Miessner purchased this bluish-gray substance that looked like sealing wax for about $3 an ounce. Selenium has the amazing property of being able to change its electrical resistance when affected by light.

Miessner explained that the Electric Dog worked with two cells of selenium behind each glass eye. When a light was flashed, and it fell on either eye, this reduced the electrical resistance of the selenium, allowing andan electrical currents to pass through. This started the motor which began turning the dog’s wheels.

If the light came through one eye; for example, the right eye, then the current would only pass through that particular eye. The way the electro-magnets and batteries were arranged would pull the rear wheel to the right. This would cause the dog to turn straight towards the light and the light would then shine into both eyes. The wheels would go straight again.

Anytime the Electric Dog saw light, he would begin to move. To demonstrate how the Electric Dog worked he put the device into action. From an electric flash, he threw light into the dog’s groggy eyes, and his invention began obediently moving toward his master. The dog would follow Miessner wherever he went with the light. The directional orientation of the dog corresponded to Miessner’s light.

Electric Dog of Hammond and Miessner: Historical Significance

The Electric Dog has great historical significance because it was one of the predecessors of modern robotics. In fact, it was considered the ancestor of all self-directing robots of a phototropic nature. Miessner saw the device as a foundation for greater inventions, including self-directing torpedoes.

Miessner also invented the selenium thief-catcher, which consists of a selenium cell with bells, guns, a camera, and a flash light. If a burglar’s dark lantern light hits the selenium eye, a wide range of noise will suddenly go off. Miessner tried the device out during a meeting at the Electric club in Chicago, seriously frightening many of the observers.

Concerning the Electric Dog, Miessner also explained how the machine could be turned into a “dog of war.” If the mechanism was readjusted, the selenium eyes could be made to pursue a dark object within light surroundings. He described how if a torpedo fitted with the same type of apparatus was launched from shore on a bright day toward an attacking fleet, the battleships would stand out as the only dark objects against a light sky. The self-directing torpedo would be able to head straight toward the target with infallible precision. 

Miessner went on to state, “A change in the mechanism makes it possible to drive your Electric Dog, or torpedo, or Zeppelin, away from you by prodding it behind with a search–light, instead of pulling it toward you.” By 1915, a radio-controlled torpedo embodied the same self-orientation device as that of Hammond and Miessner’s creation. This torpedo was stated to have almost superhuman intelligence.

All of the devices and inventions that Miessner talked about were based on the light sensitivity of selenium, and it was dubbed, “the magic eye.” A large eye can be made, composed of thousands of selenium cells.  It should be noted that the selenium cells are unequally illuminated by light from objects within their range of vision that falls on them. This will allow currents of varying strengths to pass through. The selenium cells will then light their respective glow-lamps in an exact reproduction of the shadow and light of the various objects in front of them.

“By a somewhat similar apparatus photographs have actually been transmitted by wire from Monti-Carlo to Paris, and published in the papers.” Miessner commented. Miessner was excited about the future scientific breakthroughs and endless possibilities that could occur because of the Electric Dog Seleno. It wasn’t long until other types of inventions based on selenium followed. In 1916 Centervall Huga filed a patent for an ariel torpedo that built on the work of electrical properties of selenium.

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Frequently Asked Questions

When was the Electric Dog of Hammond and Miessner invented?

The Electric Dog of Hammond and Miessner was invented in 1912.

Who invented Seleno, the Electric Dog?

Seleno, the Electric Dog was invented by the combined efforts of John Hays Hammond Jr., and Benjamin Franklin Miessner.

What did the Electric Dog do?

The Electric Dog could respond to commands and appeared to be self-powered. It “obeyed commands” of its master through the use of light signals.

How did the Electric Dog work?

The Electric Dog worked by reducing the electrical resistance of selenium when exposed to light. This allowed electrical currents to pass through and start a motor which would cause the dog’s wheels to turn. The dog then appeared to move on its own.

Why was the Electric Dog invented?

The Electric Dog was invented to explain and further understand how light signals can affect the electrical properties of selenium.

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